This invention is in the field of breath-actuated inhalation devices.
Inhalation devices for delivery of therapeutic substances to the respiratory tract of a user are now in common use. Currently available methods of generating and delivering drug formulations to the respiratory tract include metered-dose inhalers, dry powder inhalers and nebulizers. The effectiveness of such devices is limited in part by the ability to coordinate release of the formulation with inhalation. Lack of coordination between inhalation velocity and release of formulation can result in deposition of formulation in areas of the respiratory tract, such as the mouth or the throat, which wastes formulation and reduces the effective concentration of formulation in the targeted portion of the respiratory tract for systemic circulation. Ideally, the formulation should be released and delivered at a point in the user""s inhalation cycle such that particles of formulation are entrained in the breath and delivered into the desired portion of the respiratory tract. Devices which rely upon user-actuated release of formulation are particularly error prone. In such manually-operated devices, users frequently inhale too early or too late to effectively inspire the formulation. Problems associated with inefficient administration of a drug cannot always be compensated for by increasing the dose, as an accidental excessive dose of a therapeutic agent may have severe negative consequences.
Various breath-actuated inhalation devices have been developed in which discharge of medication is caused by a user""s inspiratory effort. U.S. Pat. Nos. 5,954,047; 5,848,587; and 5,823,179. Such devices do not provide a means for coordinating release of formulation with a given inspiratory flow velocity.
A hand-held, portable breath actuated device is described in U.S. Pat. No. 5,941,240. In this device, the user inhales air through an inspiratory flow path. When the inspiratory flow meets a threshold of a preprogrammed criterion, a microprocessor sends a signal to an actuator release electrical mechanism, which in turn actuates a mechanical means of forcing formulation into the flow path.
The present invention addresses the need in the art for a simple, yet effective means of regulating the timing of formulation release in response to a user""s inspiratory flow rate, and provides related advantages as well.
The present invention provides a triggering mechanism for actuating a trigger signal means upon detecting a fluid flow velocity exceeding a desired threshold. The device of the invention is capable of providing a sharp, definite signal, even in the presence of wavering or fluctuating flow velocities. Optional features of the device include provision for a delay, in which the trigger is actuated only after a preset interval following the point at which the threshold is exceeded. The trigger signal means can be operatively connected to a dispensing mechanism, whereby a transmitted signal causes a dispensing mechanism to release a volume of formulation.
The mechanism may be used in combination with a pharmaceutical inhaler, for administering a precise dosage of a pharmaceutical agent to the respiratory system of a subject or patient. The mechanism is simple, and may be disposable. Accordingly, in some embodiments, the invention provides a device for delivering an aerosolized formulation to an individual, wherein the device comprises a fluid velocity-sensitive triggering mechanism as described herein. The aerosolization devices of the invention are advantageous in that aerosol is not released below a pre-set threshold inspiratory flow rate.
In some embodiments, the triggering mechanism is configured to further provide for regulation of fluid flow rates through the mechanism. When the triggering mechanism is used in combination with an inhaler, the triggering mechanism not only controls release of formulation, but also provides greater regulation of air flow.
One aspect of the invention is a device for regulating the release and air flow of a metered dose inhaler.
Another aspect of the invention is a device for administering a metered dose of formulation, wherein said device is regulated to release the formulation over a certain range of air velocities.
An object of the invention is to provide a trigger mechanism for use in conjunction with an aerosol delivery device, wherein the trigger mechanism senses and reacts to a predetermined velocity of fluid flowing through the mechanism.
The trigger mechanism of the invention confers several advantages, among which are that it provides a simple, yet effective means for actuating an operably linked aerosolization device in response to a user""s inspiratory effort.
These and other objects, advantages, and features of the invention will become apparent to those persons skilled in the art upon reading the details of the invention, as more fully described below.